Total organic carbon of sediment core LV53-27-1 (the Sea of Japan)

Sediment core LV53-27 (41° 54′ N, 132° 33′ E) was retrieved in the northwestern Sea of Japan (Pervenets Seamount) at 1698 m depth during a joint Russian-Chinese expedition LV53 on RV "Akademik M.A. Lavrentyev" in 2010-11-10T23:39:00. Sediment core LV53-27 recovered about 120 kyr according to age model (Gorbarenko et al., 2023). 160 sediment samples, which were selected at an interval of 4 cm, were studied by the method of spore-pollen analysis. Total organic carbon content (TOC) measured by colorimetry using an AN-7529 analyser

Averaged sedimentation rates in the Northwest Pacific and Bering Sea during the first and the second oxygen isotope stages

Isotope chronostratigraphy of Upper Quaternary sediments from the Northwest Pacific and the Bering Sea was established by oxygen isotope records in planktonic and benthic foraminifera. The main regularities of temporal variations of calcium carbonate, organic carbon and opal contents, as well as of magnetic susceptibility in sediments of the study region with regard to climatic variations and productivity were established by means of isotopic-geochemical and lithophysical analyses of bottom sediments. Correlation of volcanogenic interbeds in the sediments was carried out, and their stratigraphy and age were preliminarily ascertained. Correlation was accomplished of A.P. Jouse diatom horizons determined by an analysis of the main ecological variations in diatom assemblages in Upper Quaternary sediments of the Northwest Pacific, Bering and Okhotsk Seas, and their comparison with similar variations in sediment cores with standard oxygen isotope stages. Also variations in lithology and contents of biogenic components in sediments of the region and in the cores were taken into account. A ratio of abundance of "neritic" species to the sum of "neritic" and oceanic species abundance (coefficient Id) can be a criterion of ecological changes of diatom assemblages in the studied region. It is determined by climate variability and mostly by sea ice influence. Schemes of average sedimentation rates in the Northwest Pacific and Bering Sea for periods of the first and the second oxygen isotope stages (12.5-1 and 24-12.5 ka, respectively) were plotted on the basis of obtained results and correlation of diatom horizons and lithological units in early studied cores with the oxygen isotope stages. Closure of the Bering Strait and aeration of the north-eastern shelf of the Bering Sea during the second stage induced increase of sedimentation rates in the Bering Sea, as compared with the first stage, and suspended material transport from the Bering Sea through the Kamchatka Strait into the Northwest Pacific and its accumulation in the southeast direction

Pollen record of sediment core LV53-27-1 (the Sea of Japan)

Sediment core LV53-27 (41° 54′ N, 132° 33′ E) was retrieved in the northwestern Sea of Japan (Pervenets Seamount) at 1698 m depth during a joint Russian-Chinese expedition LV53 on RV "Akademik M.A. Lavrentyev" in 2010-11-10T23:39:00. Sediment core LV53-27 recovered about 120 kyr according to age model (Gorbarenko et al., 2023). 160 sediment samples, which were selected at an interval of 4 cm, were studied by the method of spore-pollen analysis. Pollen and spores species were identified with light microscope Mikmed-2. The table shows the pollen content of the main tree taxa, which was determined for each sample. The pollen content of each taxon was determined as the proportion of this taxon in a group of trees, while all trees were taken as 100%. The paleoclimatic coefficient, is named Tp, is calculated on the basis of spore-pollen analysis. The Tp was calculated using the formula Tp = 100×Twarm/(Twarm+Tcold), where Twarm is sum of tree temperate taxa and, Tcold is sum of tree boreal taxa. In this study temperate taxa are Quercus, Juglans, Ulmus, Carpinus, Tilia, Acer, Castanea, Cryptomeria

(Table 2) Ice rafted debris abundance and accumulation rate, sedimentation rate and dry bulk density of bottom sediments from the Sea of Okhotsk

Oxygen isotope records, radiocarbon AMS data, carbonate and opal stratigraphy, sediment magnetic susceptibility, tephrachronology, and paleontological results were used to obtain detailed sediment stratigraphy and an age model for the studied cores. For studying sea-ice sedimentation an analysis of lithogenic grain number in >0.15 mm grain size fraction of bottom sediments was carried out. For quantitative estimation of intensity ice-rafting debris sedimentation number of IRD particles per sq cm per ka was calculated. Obtained results allowed to plot IRD AR distribution for the first oxygen isotope stage (0-12.5 14C ka, 14C) and for the second stage (12.5-24 14C ka). The first stage was subdivided into the latest deglaciation and the beginning of Holocene (6-12.5 14C ka) (transitive period), when the sea level was changing significantly, and the second part of Holocene (0-6 14C ka), when climate conditions and the sea level were similar to modern estimates. Data clearly show strong increase in ice formation in the glacial Sea of Okhotsk and its extent in the middle part of the sea. Average annual duration of ice coverage during glaciation was longer than that for interglaciation. However the sea ice cover was not continuous all the year round and disappeared in summer time except the far northwestern part of the sea

(Table 1) Fission ages of volcanic glass in ash layers at DSDP Hole 56-436

The fission-track technique was used to date nine samples of volcanic glasses from ash layers at Deep Sea Drilling Project Site 436. Age varied from 0.138 (+0.067 -0.063) m.y. to 12.9 (+2.11 -2.61) m.y. We annealed Sample 436-14-3 and corrected the age of annealed fossil tracks in the volcanic glass according to the resultant data. We found small differences between our age data and preliminary paleontological age data